Help Needed. Automatic Return to Neutral for New Hydro Pedal

[Bill D 1,826]

I'm trying to build a different style hydro pedal for my 416H then I did for my GT1800.  I'm having problems figuring out the return to neutral setup.  Trying to make this as close to bolt on as I can with no drilling required.

 

If I move the pedal to reverse it returns to neutral perfectly.  If I move it to forward it gets stuck.  A stronger spring would make the pedal nearly unusable and seemed to make very little difference.  Do I move the pivot point of the reverse lever or the bearing on the pedal?  Do I change the angle of the notch in the reverse lever?  I don't think a stronger spring is a good idea as it returns to neutral from reverse perfectly.  Thoughts and ideas please.  Any ideas @kpinnc since I  know you're building one as well.  Thanks, Bill

Edited September 27, 2023 by Bill D

[Gasaholic 215]

For the notch, instead of cutting it straight, could you maybe cut it curved? (think of the pull-up park brake on the old hydros - the lever that is activated by the pin on the end is curved, so roller doesn't follow a straight path) I'm thinking a slight gentle C shape on the straight edges and a radius at the bottom of the V notch just big enough for the bearing to "seat".... )

[kpinnc 11,457]

2 hours ago, Bill D said:

Any ideas @kpinnc since I  know your building one as well.  Thanks, Bill

 

Well your centering setup is pretty great Bill. About the only thing I would try is maybe moving the "bearing" closer to the pivot of the pushrod at the end. That might give it a little more authority without more spring tension.

 

Also- have you reduced the friction on the cam to see what difference it made, if any?

 

I really like your design. Very well thought out. I'm sure you'll get it perfected. 

[Lee1977 6,543]

This may not be your problem, My 520-H was imposible to get out of reverse when I got it. The cam had a groove worn in it and the came plate was worn. New parts fixed it. Might give those a check these tractors are thirty years old.

[kpinnc 11,457]

Another thought Bill: the left pedal has the return to neutral tied to the brake. You could separate the brake, and spring load the neutral cam there.

[Bill D 1,826]

9 hours ago, Gasaholic said:

For the notch, instead of cutting it straight, could you maybe cut it curved? (think of the pull-up park brake on the old hydros - the lever that is activated by the pin on the end is curved, so roller doesn't follow a straight path) I'm thinking a slight gentle C shape on the straight edges and a radius at the bottom of the V notch just big enough for the bearing to "seat".... )

Great idea but I don't have a way to cut a smooth curve in metal.

[Bill D 1,826]

9 hours ago, kpinnc said:

 

Well your centering setup is pretty great Bill. About the only thing I would try is maybe moving the "bearing" closer to the pivot of the pushrod at the end. That might give it a little more authority without more spring tension.

 

Also- have you reduced the friction on the cam to see what difference it made, if any?

 

I really like your design. Very well thought out. I'm sure you'll get it perfected. 

Thanks for the idea.  I think I'll try moving it in both directions and see what happens.  For some strange reason I remember that shortening the distance between the frame pivot bear made more difference than going the other way.

[Bill D 1,826]

8 hours ago, Lee1977 said:

This may not be your problem, My 520-H was imposible to get out of reverse when I got it. The cam had a groove worn in it and the came plate was worn. New parts fixed it. Might give those a check these tractors are thirty years old.

Thanks for the idea.  Everything is s in good shape there.  This tractor only has 193 hours on it.

[Bill D 1,826]

7 hours ago, kpinnc said:

Another thought Bill: the left pedal has the return to neutral tied to the brake. You could separate the brake, and spring load the neutral cam there.

Sounds similar to Matt's pedal kit.  Does anyone have any engineering drawings of his return to neutral setup?  Might be easier to copy it.

[Gasaholic 215]

10 hours ago, Bill D said:

Great idea but I don't have a way to cut a smooth curve in metal.

Cheap 9 inch tabletop bandsaw with metal cutting blade? (I got a Skil 9 inch bandsaw for my wood shop for under $200 on Amazon, it'd take metal cutting blades, Though, TBH, it would be slow going, and probably some touch-up work with a file or dremel..) 

[Bill D 1,826]

Well this is what I came up with.  This is a true bolt on hydro pedal with no drilling required for this application (1994 416H), just run a 5/16" self tapping bolt in an existing punched hole.  Pedal pressure is a little heavy.  I may have to try a different spring.  Drives well.  Pedal is slow to return when going full speed down the hill on the road in front of my house, but works fine otherwise.  Thanks to all for the advice.  Feel free to copy at your own risk 😉.

[kpinnc 11,457]

1 hour ago, Bill D said:

Well this is what I came up with. 

 

Very nice Bill. The centering parts are functional without being overly complex. Much smarter design than any I've seen so far.

 

Everything I've made has too many moving parts. Guess I overthink everything...

 

I like that you were able to keep the pushrod straight too. Well done! 

Edited September 24, 2023 by kpinnc

[Bill D 1,826]

1 hour ago, kpinnc said:

 

Very nice Bill. The centering parts are functional without being overly complex. Much smarter design than any I've seen so far.

 

Everything I've made has too many moving parts. Guess I overthink everything...

 

I like that you were able to keep the pushrod straight too. Well done! 

Thanks for the compliment.  I sleeved the push rod with plastic tubing to prevent wire abrasion.  I've thought about moving the push rod closer to the pivot point for the pedal so it'll be less touchy, but I'd have to up size the rod to 3/8" and bend it to clear the steering fan gear.  Going to try mowing with it and see how I like it.  Pedal pressure is a little stiffer than I expected, especially reverse.  Not sure why.  Something to tweak I guess. The push rod in the picture was part of my original design.  I sleeved the end of the heim joints with plastic tubing.

Edited September 24, 2023 by Bill D

[Bill D 1,826]

What's your opinion @Damien Walker?

[Handy Don 11,846]

I really like that you elected to start with a very simple design and will work from there to improve! Like @kpinnc, I tend to spend tons of time mentally optimizing since I really dislike redos.

 

12 hours ago, Bill D said:

Pedal pressure is a little stiffer than I expected, especially reverse.

The reason for the harder reverse (which may not be a bad thing?) is leverage

 

The spring force (blue arrow) is being offset by either the force from the forward (red arrow) or reverse (green arrow) movement of the pedal.

The forward force is being applied closer to the spring so it has more leverage than the reverse force which is farther from the spring.

 

One option might be to put the pivot to the right and the spring to the left of the “V” to make reverse easier than forward but that doesn’t solve the problem of wanting both forces to be similar.

Another is to make the reverse pedal arm longer so it has more leverage.

 

 

 

Another (and yes, adding complexity!) is to have make two stacked “return” arms, each applying return force from only one direction.

The “forward” return would have a slope to return it to neutral  from forward motion but be curved downward so it applies no force to return from reverse. The second arm would be the opposite. Each would have their own spring (maybe with a barrel adjuster?) for independent tension.

 

[Bill D 1,826]

50 minutes ago, Handy Don said:

I really like that you elected to start with a very simple design and will work from there to improve! Like @kpinnc, I tend to spend tons of time mentally optimizing since I really dislike redos.

 

The reason for the harder reverse (which may not be a bad thing?) is leverage

 

The spring force (blue arrow) is being offset by either the force from the forward (red arrow) or reverse (green arrow) movement of the pedal.

The forward force is being applied closer to the spring so it has more leverage than the reverse force which is farther from the spring.

 

One option might be to put the pivot to the right and the spring to the left of the “V” to make reverse easier than forward but that doesn’t solve the problem of wanting both forces to be similar.

Another is to make the reverse pedal arm longer so it has more leverage.

 

 

 

Another (and yes, adding complexity!) is to have make two stacked “return” arms, each applying return force from only one direction.

The “forward” return would have a slope to return it to neutral  from forward motion but be curved downward so it applies no force to return from reverse. The second arm would be the opposite. Each would have their own spring (maybe with a barrel adjuster?) for independent tension.

 

I like your idea, but space between the belt and frame is limited so stacking two return arms is probably not going to work.  As it is now I'm going to cut the end of the bolt down so the belt doesn't hit it when it slaps around.  I wonder if moving the pivot point of the return arm would help at all. 

 

When I read the instructions for Matt's kit I noticed that where you drill the hole for the bearing on the auto return is offset slightly from center as is the stock return to neutral pivot when you press the brake.  I'm wondering how that affects operation of his neutral return.  Thoughts?

[wallfish 16,739]

On 9/22/2023 at 11:11 PM, Bill D said:

Great idea but I don't have a way to cut a smooth curve in metal.

Cut the V just a little smaller than the final size required and grind the curve into those flats until the final size.

 

[Handy Don 11,846]

2 hours ago, Bill D said:

I like your idea, but space between the belt and frame is limited so stacking two return arms is probably not going to work.  As it is now I'm going to cut the end of the bolt down so the belt doesn't hit it when it slaps around.  I wonder if moving the pivot point of the return arm would help at all. 

 

When I read the instructions for Matt's kit I noticed that where you drill the hole for the bearing on the auto return is offset slightly from center as is the stock return to neutral pivot when you press the brake.  I'm wondering how that affects operation of his neutral return.  Thoughts?

I can see that pivot bolt being quite close to the belt could involve touching and wear, yeah, not ideal. 

Sticking with the stacked arms using ⅛” plate (or not!) I’d consider a round-headed, Allen socket bolt with a bushing, shim, and spacer. A single roller can ride on both return arms. I think this would fit. The bushing allows tightening the bolt and keeps the arm from rubbing on threads, which would accelerate wear.

 

 

The axle of the follower roller traces an arc around the pedal pivot as the pedal moves from reverse to forward.  I think your goal is to have the force on the follower moving it from either end of the arc toward the center be the roughly the same. To do that you either need symmetry or separately controlled forces (shameless plug for stacked arms 😁).

Achieving symmetry means having the same “leverage times force” for both reverse and forward.

 

You’ve already got the return control arm and the control lever close to perpendicular to each other (very important). But, because the return control arm is on a pivot, when the follower “climbs the V” it causes the control arm to rotate further for reverse than for forward! More rotation = more pull on the spring. Keeping the same general design, there are three ways to mitigate this so that the arm rotates closer to the same amount for climbing either side of the V:

One way is move the arm’s pivot farther from the V (to the left, in this case)

Another way is to make the V asymmetric so that the slope of the reverse direction is shallower than the slope in the forward direction.

The last way is to keep the symmetric V and adjust the angle at which the return control arm intersects with the control lever so that the effective leverage is equal in both directions. (Simultaneous equations anyone?)

[kpinnc 11,457]

5 hours ago, Handy Don said:

I tend to spend tons of time mentally optimizing since I really dislike redos.

 

I'm using that one Don. A perfect excuse with included reasoning in the same sentence! That's what I call irrefutable! 

[kpinnc 11,457]

20 minutes ago, Handy Don said:

The last way is to keep the symmetric V and adjust the angle at which the return control arm intersects with the control lever so that the effective leverage is equal in both directions. (Simultaneous equations anyone?)

 

Dear Lord in the same post you drop THIS? I can't wrap my tiny noggin around that one!  

 

...More pictures, less words.  

 

Just joking of course. My mods typically end at "will I break it"!

Edited September 24, 2023 by kpinnc

[Handy Don 11,846]

 

 

41 minutes ago, Handy Don said:

Simultaneous equations anyone

These were among my standard tools as a systems analyst. Actually, in this case, getting an exact answer would require calculus. 

 

24 minutes ago, kpinnc said:

can't wrap my tiny noggin around that one

Apologies.

 

24 minutes ago, kpinnc said:

More pictures

If @Bill D wants to pursue, I’ll get out the CAD software. 🙂

 

23 minutes ago, kpinnc said:

My mods typically end at "will I break it"!

Calculus will likely NOT provide that answer! 🤣

[Bill D 1,826]

1 hour ago, Handy Don said:

I can see that pivot bolt being quite close to the belt could involve touching and wear, yeah, not ideal. 

Sticking with the stacked arms using ⅛” plate (or not!) I’d consider a round-headed, Allen socket bolt with a bushing, shim, and spacer. A single roller can ride on both return arms. I think this would fit. The bushing allows tightening the bolt and keeps the arm from rubbing on threads, which would accelerate wear.

 

 

The axle of the follower roller traces an arc around the pedal pivot as the pedal moves from reverse to forward.  I think your goal is to have the force on the follower moving it from either end of the arc toward the center be the roughly the same. To do that you either need symmetry or separately controlled forces (shameless plug for stacked arms 😁).

Achieving symmetry means having the same “leverage times force” for both reverse and forward.

 

You’ve already got the return control arm and the control lever close to perpendicular to each other (very important). But, because the return control arm is on a pivot, when the follower “climbs the V” it causes the control arm to rotate further for reverse than for forward! More rotation = more pull on the spring. Keeping the same general design, there are three ways to mitigate this so that the arm rotates closer to the same amount for climbing either side of the V:

One way is move the arm’s pivot farther from the V (to the left, in this case)

Another way is to make the V asymmetric so that the slope of the reverse direction is shallower than the slope in the forward direction.

The last way is to keep the symmetric V and adjust the angle at which the return control arm intersects with the control lever so that the effective leverage is equal in both directions. (Simultaneous equations anyone?)

Thanks @Handy Don.  I think you confirmed something I was already thinking.  If I make the reverse angle shallower that would probably fix my pedal pressure issued in reverse. It's the last 1/2" of travel in reverse that makes the pedal pressure an issue.  Easy enough to cut the notch a little more.  Probably the simplest fix as well.  If you're really bored feel free to break out the AutoCAD.  Pivot center to bearing center is 4 1/8".

Edited September 24, 2023 by Bill D

[wallfish 16,739]

5 hours ago, Bill D said:

I tend to spend tons of time mentally optimizing since I really dislike redos.

I'm 180 degrees from that and spend tons of time on the redos! My hands can work better than my brain!

But that's why I enjoy talking and collaborating on stuff with you Don.  Different points of view can unlock things that weren't realized by either

Edited September 24, 2023 by wallfish

[Bill D 1,826]

2 minutes ago, wallfish said:

I'm 180 degrees from that and spend tons of time on the redos! My hands can work better than my brain!

But that's why I enjoy talking and collaborating on stuff with you Don.  Different points of view can unlock things weren't realized by either

Definitely. Thanks to everyone for the help and ideas.

[Handy Don 11,846]

5 minutes ago, Bill D said:

Thanks @Handy Don.  I think you confirmed something I was already thinking.  If I make the reverse angle shallower that would probably fix my pedal pressure issued in reverse. It's the last 1/2" of travel in reverse that makes the pedal pressure an issue.  Easy enough to cut the notch a little more.  Probably the simplest fix as well.

You're welcome.

Re-doing the pivot may help the clearance issue, as well.

 

The hole positions you mention might have some effect but it’s tough to determine exactly. The trick is managing the intersection of the arc traced by the follower with the arc at each point of the V as the follower moves. You might just want to post some measurements for the full forward and reverse positions as well as the neutral position. Then its just arithmetic!